Sigma LBA-400 Manuel D’Utilisation

Ultracal! every 10 to 15 minutes, or whenever you think your camera may have strayed.  This drift 

can be observed as changes in the background noise image.  Un-illuminated areas will appear as gray 

and dark violet (almost black) random noise.  If the background starts to look too gray then the 
baseline is drifting negative.  If too dark, then the baseline is drifting positive.  Note:  These colors 

apply to the Continuous 128 color palette.  They change depending upon the palette selection. 

 

The clip level is a processed 

energy

 pixel value.  Only those pixel values that exceed the clip level are 

used in computing the following results: 

•  Beam Widths, if Percent of Energy or Peak methods are selected. 
•  Centroid Location. 
•  Elliptical beam Orientation. 
•  Top Hat:  Mean, Standard Deviation, Min and Max, when in Data mode only. 
•  Effective Area. 

Depending upon the Beam Width Method, the clip level value is determined as follows: 

•  With the 4-Sigma and Knife-Edge methods and with the Top Hat results disabled, the LBA 

totals the pixel 

energy

 values in descending order until it finds the pixel which causes the sum to 

exceed 86.5% of the total 

energy

 value.  The raw 

energy

 value of this pixel becomes the clip 

level. 

•  With the 4-Sigma and Knife-Edge methods and with the Top Hat results enabled, the LBA 

sets the clip level to the value that is equal to 80% of the current peak 

energy

 value. 

•  With the Percent of Energy method, the LBA totals the pixel energy values in descending order 

until it finds the pixel which causes the sum to exceed the set Clip% of the total 

energy

 value.  

The 

energy 

 value of this pixel becomes the clip level. 

•  With the Percent of Peak method, the LBA sets the clip level to the value that is equal to the 

set Clip% of the current peak 

energy

 value. 

The number of pixels with values above the clip level establishes the Effective Area of the beam.  The 

locations of the pixels with values above the clip level are used to determine the beam's Centroid 

Location and Elliptical beam Orientation. 

 

 

The cameras used with the LBA-PC are not calibrated to directly provide 

energy

 of a laser beam.  The 

Energy of Beam dialog box edit control lets you calibrate the LBA-PC to the 

energy

 of your laser.  You 

must measure the 

energy

 of your beam using an external measuring device, then enter the 

energy

 

here.  The value entered must be the total 

energy

 of the beam for the frame currently displayed.  For 

accurate results, the beam must fit inside of the current Pan/Zoom window. 
If you enter a calibrated value of zero, the Total, Peak, Gauss Height(s), and Top Hat results are 

displayed as processed digitizer values.  Any entry other than zero will immediately appear as the Total 

Operator’s Manual 

 

LBA-PC 

 

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